1. Field of the Invention
Fabric-conditioning has taken on increasing importance with increased use of synthetic fibers in articles of clothing. Such synthetic fabrics are usually initially treated with conditioning agents by the manufacturers, but washing or dry cleaning the fabrics tends to remove the conditioning agents.
Various methods have been proposed to apply fabric-conditioning agents to fabrics to improve their various properties. Such fabric-conditioning agents include softeners, antistats, lubricants, bacteriostats, mildew-proofers, moth-proofers and the like. The methods of application include treatment of the fabrics by padding, dipping, spraying, and rinsing with liquid solutions of the condition agents.
The inconvenience of adding fabric softeners at the rinse cycle has generated interest in fabric-conditioning products which may be added to the clothes dryer to tumble with, and thereby condition, the drying clothes. Applying fabric-softeners in the dryer offers an important convenience because the softeners can be added at the time the clothes dryer is loaded. In addition, the softeners can be applied directly from a solid substrate in solid form, as contrasted with the dilute solutions used in the final rinse cycle of the clothes washing process.
Two important considerations for a fabric-conditioning article used in the clothes dryer are: first, that it be capable of transferring conditioning materials to the fabrics uniformly without staining; and, second, that it remain in effective contact with the clothes when tumbled therewith. Some of the prior conditioning compositions tended to stain the fabrics due to spotty, irregular transfer. The success of the article depends on uniform release and transfer of the conditioning agents to the fabrics being treated to obtain sightly and effectively conditioned clothes.
2. Prior Art
Dryer-administered fabric-softeners are disclosed in U.S. Pat. Nos. 3,442,692; 3,686,025; 3,895,128; 3,944,694; 3,967,008; 4,000,340; 4,022,938; 4,127,694 and others. Commercially available fabric-softener articles include flexible non-woven substrates carrying softeners, and polyurethane sponges carrying fabric-softeners. A third type comprises a fabric bag containing powdered fabric-softeners. The bag containing the softeners is secured to a surface on the dryer drum. The softener is said to be released from the bag, and to transfer to the clothes tumbled in the dryer over a number of dryer loads. Other types of carrier articles have been proposed, including styrofoam articles impregnated with fabric-softeners and other dispensing devices which may be fixed to a wall of the dryer in such a way as to contact the tumbling clothes.
U.S. Pat. No. 4,000,340 is directed to a dryer-administered fabric-softener article in which the main component is a "crisping agent." Such "crisping agents" include alcohols, carboxylic acids and carboxylic acid salts. Adjuncts for such crisping agents are also disclosed, and include "waxy" esters, that is mono-, di- and triglyceride carboxylic acid esters. The dispensing means described include hollow sponges, cloth, or paper bags, sheets of paper or woven or non-woven fabric, preferably having an open or porous structure.
Various sorbitan adjuvant products in combination with a dryer administered fabric-softener article are disclosed in U.S. Pat. No. 4,022,938. Release functions are described for these compounds, which are used with a major amount of cationic fabric-softeners. There is no mention here of fatty glyceride spreading agents.
U.S. Pat. No. 4,127,694 issued Nov. 28, 1978, discloses the combination of water-soluble nonionic antistatic agents in combination with glyceride softeners, which do not have substantial antistatic properties. Because the antistatic agents are water-soluble, they are preferably applied in the clothes dryer. The glyceride materials used are mixtures of mono-, di-, and triglycerides having flow properties in the dryer operating temperature range, said to provide even distribution of the nonionic fabric-conditioning materials onto the clothes in an automatic dryer. The substrate materials include sponges, cloth or paper bags, flexible paper, and woven or non-woven cloth. Optional ingredients include quaternary ammonium antistatic and fabric-softening agents, but the quaternary ammonium compound replaced only one-tenth of the glyceride mixture in Example II (Column 11, lines 24-27).